/*
 * Copyright 2007-present the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.maven.wrapper;

import java.io.File;
import java.math.BigInteger;
import java.net.URI;
import java.security.MessageDigest;

/**
 * @author Hans Dockter
 */
public class PathAssembler {
  public static final String MAVEN_USER_HOME_STRING = "MAVEN_USER_HOME";

  public static final String PROJECT_STRING = "PROJECT";

  private File mavenUserHome;

  public PathAssembler() {
  }

  public PathAssembler(File mavenUserHome) {
    this.mavenUserHome = mavenUserHome;
  }

  /**
   * Determines the local locations for the distribution to use given the supplied configuration.
   */
  public LocalDistribution getDistribution(WrapperConfiguration configuration) {
    String baseName = getDistName(configuration.getDistribution());
    String distName = removeExtension(baseName);
    String rootDirName = rootDirName(distName, configuration);
    File distDir = new File(getBaseDir(configuration.getDistributionBase()), configuration.getDistributionPath() + "/" + rootDirName);
    File distZip = new File(getBaseDir(configuration.getZipBase()), configuration.getZipPath() + "/" + rootDirName + "/" + baseName);
    return new LocalDistribution(distDir, distZip);
  }

  private String rootDirName(String distName, WrapperConfiguration configuration) {
    String urlHash = getMd5Hash(configuration.getDistribution().toString());
    return String.format("%s/%s", distName, urlHash);
  }

  private String getMd5Hash(String string) {
    try {
      MessageDigest messageDigest = MessageDigest.getInstance("MD5");
      byte[] bytes = string.getBytes();
      messageDigest.update(bytes);
      return new BigInteger(1, messageDigest.digest()).toString(32);
    } catch (Exception e) {
      throw new RuntimeException("Could not hash input string.", e);
    }
  }

  private String removeExtension(String name) {
    int p = name.lastIndexOf(".");
    if (p < 0) {
      return name;
    }
    return name.substring(0, p);
  }

  private String getDistName(URI distUrl) {
    String path = distUrl.getPath();
    int p = path.lastIndexOf("/");
    if (p < 0) {
      return path;
    }
    return path.substring(p + 1);
  }

  private File getBaseDir(String base) {
    if (base.equals(MAVEN_USER_HOME_STRING)) {
      return mavenUserHome;
    } else if (base.equals(PROJECT_STRING)) {
      return new File(System.getProperty("user.dir"));
    } else {
      throw new RuntimeException("Base: " + base + " is unknown");
    }
  }

  public class LocalDistribution {
    private final File distZip;

    private final File distDir;

    public LocalDistribution(File distDir, File distZip) {
      this.distDir = distDir;
      this.distZip = distZip;
    }

    /**
     * Returns the location to install the distribution into.
     */
    public File getDistributionDir() {
      return distDir;
    }

    /**
     * Returns the location to install the distribution ZIP file to.
     */
    public File getZipFile() {
      return distZip;
    }
  }
}
